主句 I will investigate some of the adverse effects within market economies around the globe.
television advertising has on viewers 是定语从句修饰the adverse effects.它在定语从句中做has 的宾语,所以省略了关系词.
此句可以翻译为：我将要在全球的经济市场内调查电视广告对于电视观众的不利影响.